Combination double-muffle preheating and heat-treating furnace



J. A. GASKILL.

COMBINATION DOUBLE MUFFLE PREHEATING AND HEAT TREATING FURNACE.

APPLICATION FILED MAY 23, I919.

Patented. Jan. ML, 1922.

L IMS JkMES fl @5 3 mu.

skilled in the'art to which it I UNHTED STATES PATENT controls.v

JAMES A. GASKILI, OF CLEVELAND, OHIO.

essrs.

' T 0 all tvhom it may concern:

Be it known that I, J AMES A. GASKILL, a citizen of the United States, and resident of Cleveland, in the county of Cuyahoga and State ofOhio, have invented certain new and useful Improvements in Combination Double-Mufile Preheating and Heat- 'Treating Furnaces, of which I hereby de-' clare the following to be a full, clear, and exact descript'on, such as will enable others appertains to make and use the same.

The objects of the invention are to pro vide a closed furnace for heat treating steel and other alloys, in which the metal is treated by radiation and conduction while confined in a muffle, instead of by contact with the products of combustion, as in an open hearth furnace.

By this means the metal is prevented from absorbing injurious gases and impurities from the heating agencies, and is also heated more uniformly and is protected from blasts of cold air, which decarbonize and crack or blister the steel; other advantages are found in the manner of construction which pro tects the operator from blasts of flame.

It includes a main co bustion chamber which is employed as a heating chamber. and means for obtaining a super-heated air blast which enables the operator to raise the temperature at the combustion point more quickly, and also in conjunction with the use of oil or gas to obtain a better control of the treat and at lesscost for fuel. The hot air will also vaporize the oil and prevent the burner from clogging, and also prolon the life of the crucible, or muflie.

The invention includes a pre-heating chamber, supplied with heat from the combustion chamber and in which metal parts to be treated are enclosed in a muflie. In this chamber the temperature is increased gradually in the metal to be subjected to the Jhigher temperatures of the, combustion chamber, before introducing them therein.

This pre-heating chamber is also employed as a drawing chamber, for reducing the temperature of hardened products which have been previously treated in the; combustion or main heating chamber. By means of the pre-heating chamber the temperature is reduced or drawngradually to bring the metal to the color required.

Theobjects of employing first the preheating and afterwards the heat-treating Specification of Letters Patent.

chamber are also to prevent warping and lrregular heating of the metal products.

The combustion chamber is also so constructed that it can be converted into a melting furnace by removing the upper preheating chamber and substituting a crucible for a muflie therein:

The furnace is also designed to take the place of the more expensive electric furnaces and for melting all ordinary material such as steel, semi-steel, grey iron, all high alloyed steels or low carbon steel, and all other metal alloys or glass, and will Produce a temperature of 3,000 degrees and upward according to the number of burners employed.

The air blast-is automatically heated before commingling with the fuel by contact with the heated walls of the combustion chamber, which it traverses in a spiral direction in an unobstructed annular chamber,-in which the pressure and temperature of the blast are equalized at all the outlet nozzles.

The addition of the super-heated air to the oil fuel quickly raises the temperature of the furnacewhich increases in degree as long as the furnace is in use.

The invention comprises, the combination and arrangement of parts and construction of the varlous details hereinafter described, shown in the accompanying drawings and specifically pointed out in the claims.

In the drawings Fig. 1 is a vertical section of the combined heat treating and preheating and drawing chambers. Fig. 2 is a plan thereof. Fig. 3 is a plan of the bottom doors of the furnace. Fig. 4: is a longitudinal section of a combination gas and oilfuel burner adapted for use in this furnace.

In these views A is the outer wall of the combustion chamber, B is an annular air chamber encircling the same, C is the inner wall and D is a fire brick lining having a projecting portion D intermediate of the top and bottom. Underneath the projection or shoulder D formed thereby, the burner nozzles E, -E, discharge into the combustion chamber F and underneath the muflle Patented Jan. Ill), 1922.-

Application filed May 23, 1919. Serial No. 299,365.

which contains the metal products to be- .chamberH underneath the mufiie and a heat expanding and retarding chamber I at the top of the chamber. Thisconstruction pre- 1 vents the direct escape of the hot products of nozzles.

air to expand and become highly rarefied bycombustion and retains them in' close proximity to the mufiie. K

The air blast is introduced tangentially at B near the base of the combustion chamber and the air passes spirally upward through the open unobstructed annular air chamber in, close contact with the wallsof the chamber and issues through pipes J, J,of reduced size at the upper end. The air is then carried downward into the mixing chambers K, K, through which the fuel supply nozzles L, L, pass and into discharge nozzles E, E. Valves M, M, control the fuel supply and valves N, N, control the air supply to the The annular chamber B permits the the extreme heat of the combustion chamber, and since it containsla large volume of air at a time the pressure and temperature therein will become equalized before it issues from the pipes J, J.

In Fig. 4 a form of burner is shown adapted for use. alternately with fuel and gas. Here 0 is an oil supply pipe having a fine terminal orifice 0 through which the oil is projected. Concentrically arranged in relation thereto is a gas supply pipe P hav-.

ing perforations P at its outer end through which the gas is discharged. 0 and P are the respective oil and gas pipes leading .to a common union P In the combustion or heattreating chamber, a mufile G is supported upon brick G,

and the furnace is provided with a door G which gives access thereto. The mufile closes the opening G in the chamber wall through which it is introduced and prevents the blast from injuring the face of the operator. A 'pyrometer'tube R is inserted in the mufl'le through the rear of the chamber. A central opening S is formed in the bottom of the chamber to take care of occasional overflow from the muffle. Thisopening is continued through the edges of the folding doors, T, T, which can be-dropped if necessary to, discharge the contents of the chamber or repair a the lining. A heavy tile V covers the top of the combustion chamber and the draft issues through the central opening V into the pre-heating and drawing chamber W. This chamber contains the muflle W into whlch the metal products w be heat treated 'ar e first introduced to removethe chill and to and the temperature can be gradually raised until they can be introduced inte the main chamber with safety.

The combustion chamber can be employed as a melting furnace by removing the upper chamber and substitutlng a crucible for th muflle in the combustion chamber.

The use of the hot air blast in this furnace serves to produce a higher degree of temperature than could be otherwise obtained with oil fuel, because the dry hot'air assists in vaporizing the fuel and prevents the deposit of carbon in the burner. It also prolongs the life of the muflleor crucible for the reason that the air blast is perfectly dry and hot and will not'have the disintegrating effeet that a moist, cold, air blast, would have, and therefore a correspondingly greater number of heats can be obtained from each container. r p

The air is forced into the air chamber under pressure from any source such as a blower or fan, and circulates circumferentially around the furnace and since it is com pressed in the air chamber there is no danger of its being released before it becomes uniformly heated. throughout. It will be noticed also that the outlet pipes J, J, are of less diameter than the inlet pipe B.

A door at Z is employed for igniting the fuel and for-expansion ofthe products of combustion at the time of lighting.

Having described the invention what I 7 claim asnew Patent is 1. A heat treating furnace comprising, a combustion chamber, a cover having acentral opening, an annular air compression chamber enclosing the walls of said comand desire to secure by Letters bustion chamber, a tangentially placed inlet pipe for air at the base of-said air chamber, tangentiaLfuel burner nozzles discharging in said combustion chamber, a mixing chamber for fuel and air communicating with each burner nozzle, air passages leading from'said air chamber and communicating with said mixing chambers and a muflie horizontally supported in said combustion chamber said. mufiie extending through the walls of said. combustion chamber and air chamber, and a door in the outer wall of said air chamber giving access to said muflie. '2. In a heat treating fufnace, a combusthereon, a coverrfor said combustion chamber provided with an opening for the passage of the products of combustion from the said combustion chamber tothe preheating chamber, a bottom for the main chamber provided with an opening, a mufie supported in each chamber, a fuel burner nozzle entering said combustion chamber, and means for supplying a mixture of fuel oil and superheated air to said burners.

4. In a furnace, a combustion chamber, burner nozzles extending therein, fuel supply pipes and air mixers thereon, an annular air chamber heated by said combustion chamber and enclosing the same for supply ing hot air under uniform pressure and temperature to said mixers, said supply pipes extending through said mixers. communicating with said nozzles. said and v nozzles. extending tangentially into said 20 combustion chamber.

5. In a furnace, a combustion chamber, a pre-heating chamber supplied with heat 1 thereby, burner nozzles entering'the combustion. chamber tangentially, burner supply pipes and air mixers communicating with said burner nozzles, an exterior annular air chamber enclosing said combustion chamher, an airinldt pipe extending tangentially into said air chamber adjacent to its base, and air outlet pipes communicating with said mixers.

In testimony whereof, hand this lth day of January, 1919.

JAMES A. GASKILL. In presence of- R. W. JEREMIAH, WM. M. MONROE.

I hereunto set my 

